init repo and add code

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "kbd-bl"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "kbd-bl"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

src/main.rs

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+use std::env;
+use std::fs;
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    let value = &args[1];
+    let parsed = value.trim().parse::<i32>();
+
+    if parsed.is_err() {
+        panic!("Value entered ({}) is not number", value);
+    }
+
+    let parsed_value = parsed.unwrap();
+
+    if parsed_value > 255 {
+        panic!("value entered ({}) must be <= 255", value);
+    }
+
+    if parsed_value < 0 {
+        panic!("value entered ({}) must be >= 0", value);
+    }
+
+    fs::write("/sys/class/leds/kbd_backlight/brightness", value)
+        .expect("Something went wrong writing to file")
+}